Population structure and regeneration status of woody species in a remnant tropical forest: A case study of South Nandi forest, Kenya

Abstract

The study was conducted to investigate the population structure and regeneration status of South Nandi forest and document uses of trees using 35 nested - plots of size 600 m2 (30 m × 20 m) each. A total of 68 species from 37 families and 60 genera of woody plants were encountered in the study area. The plants were categorized into seedlings, saplings and adults based on DBH classes then status of natural regeneration category determined. A Shannon-Weinner index mean value of 2.64 was obtained suggesting high species diversity in South Nandi forest. About 16.2% of woody species in the forest showed none to poor regeneration; good to fair regeneration (36.6%) and new regeneration of 47.2%.The population structure of the woody species showed an inverse-J curve when all species were considered. However, individual species showed varying patterns; for example, Olea capensis, Albizia gummifera, Maesopsis eminii and Mimulopsis arborenscens did not show the inverse -J curve. The density and basal area for whole forest was 537.3 ± 74.8 stems ha−1 and 26.8 ± 12.0 m2ha-1 respectively. Solanum mauritianum has become invasive in the forest and quick action is required to check its spread. Species with low Importance Value indices and those species with none to poor regeneration status should be prioritized for conservation. Over 78% of the plant species had multiple uses suggesting that this forest played an important role in the household's subsistence and income contribution. Detailed regeneration studies are recommended to fully understand the causes and probable mechanisms that could promote natural regeneration.